"But sharing copyrighted material should by no means be considered something that is a social principle."
It is, in fact. My friends don't have to pay royalties to content creators when they look at paintings I have hanging up in my house, watch a movie I rented, or borrow a book from me. This isn't because we don't respect copyright as a society, but because we recognize that sharing is a natural human activity, and the measures required to enforce the prevention of such behavior would create a society without freedom or privacy that no one wants to live in.
For similar reasons, what I choose to upload and download on a p2p network is no one's business but mine and the peer I've connected to. They are in effect private conversations, and any legal system that requires monitoring of these private conversations will, carried to its logical conclusion, eliminate all privacy and freedom in digital life, since any single packet on the network, whether it's for email, web traffic, or any other use, could conceivably contain copyrighted bit sequences and therefore be marked for inspection. Similarly, every file on our computers would obviously need to be scanned at borders and other checkpoints to be sure no one had infringing bit sequences on their systems.
Look, there have been plenty of examples that show that a significant percentage of people are willing to pay for digital content even when they could otherwise obtain it freely through file sharing, whether out of respect content creators, or for the sake of quality and convenience. So this isn't a question of whether or not copyrighted digital content can survive--it's been well proven that it can survive and thrive. No, the question is whether we should allow a few entrenched stakeholders to trample our civil rights in order to milk a bit of extra revenue out of the system without having to innovate in response to new cultural norms.